To define the prevalence of coronary artery disease (CAD), both overt and latent, in a free-living population, we have performed exercise thallium scintigraphy in collaboration with the Johns Hopkins University, Division of Cardiology in approximately 500 individuals from the BLSA. Preliminary analysis of these data has shown an age-related increase in the prevalence of both overt and latent CAD. We have also found that the incidence of subsequent coronary events (angina, myocardial infarction or cardiac death) in asymptomatic subjects is strikingly high in the subset whose thallium scan and exercise ECG are both abnormal. We have also used thallium scintigraphy and exercise ECGs to define a group of men and women ostensibly free from CAD in whom left ventricular function has been measured during maximal bicycle exercise by radionuclide angiography (MUGA), also in conjunction with Johns Hopkins. In these carefully selected subjects, maximal cardiac output did not decline with age -- contrary to the body of literature in less intensively screened individuals. Nevertheless, the methods of achieving maximal cardiac output were found to differ with age, the young attaining a more rapid heart rate and more complete systolic emptying, whereas the elderly depended more upon the Frank-Starling mechanism, i.e. dilation of the heart during the filling period. Although maximum diastolic filling rate at rest declined with age, no such age relationship was seen during exercise at a 100 watt workload. Thus, the age-related diminution in early diastolic filllng rate at rest which has been documented in the BLSA population both by echocardiographic and radionuclide techniques, does not appear to limit diastolic filling during exercise.